Scanning Robert's Expert Texture link blog, I see a link to Fred Chong over at MSDN. Fred is a solutions architect at Microsoft, and he's been thinking a lot about SaaS.
In his latest post (SaaS is a journey, walk with us), he gives the table of contents of a book about that he and Gianpaolo are writing about SaaS.
The outline looks great; his summary of key points for architects is perfect:
At my previous startup, Energy Interactive, we offered a product in the electric industry that we offered as an ASP (that's what we called SaaS back in the twentieth century). We went through everything Fred describes--only we weren't lucky enough to have a book to help us along!
Scale the application Enable multi-tenant data Facilitate customization
The issues we had with scaling are part of what convinced us that we needed to start Digipede--it just wasn't easy to scale an application. When we looked around our datacenter and saw so many servers that could have been used (and even more when we looked around the rest our enterprise), we wanted an easy way to take an application and scale it out. The tools just weren't out there.
One nit with the table of contents: Fred's chapter on scaling doesn't seem to address distributed or grid computing at all. I'm a little surprised by that. Given the adaptability of grid to service oriented architecture (and I certainly view SaaS as a flavor of SOA) that has been noted lately by experts like Lee Liming and Greg Nawrocki, it seems that Fred and Gianpaolo would mention it. Fred lists the following issues:
How can you scale that application to a cluster? To a data center? How do you plan your hardware so you can handle peak demand without overspending? Whether grid is the answer or not, I'm certain that much SaaS will involve some flavor of distributed computing, and I hope these two go into some detail there.
Pools: thread, connections etc. Async Locks States UI/Presentation
By the way, it looks like Fred and Gianpaolo are going to cover a lot more than just technical issues--they've got chapters planned on everything from Business Model to Security to Instrumentation and Monitoring. That's fantastic. SaaS is so different in so many ways from traditional enterprise software, and I'm glad to see Microsoft folks lending their considerable wisdom and experience to help people along.